Simpler: write the abscissæ equation for the intersection of the parabola and the line: $$ax^2+bx=3x-2\iff ax^2+(b-3)x+2=0.$$ The line is tangent to the parabola if and only if this quadratic equation has a double root, and the point of contact is $(1,1)$ if and only if the double root is $x=1$.
Can you take it from here?